/*******************************************************************
   After Monty Python (Sir Bedevere).
   © L. Allison - http://www.allisons.org/ll/
   Source: http://www.allisons.org/ll/Logic/Prolog/Examples/witch/
*******************************************************************/

witch(X) :- burns(X),
            female(X).

burns(X) :- wooden(X).

wooden(X) :- floats(X).
wooden(woodBridge).
stone(stoneBridge).

floats(bread).
floats(apple).
floats(cherry).
floats(X) :- sameweight(duck, X).

female(girl).          % by observation
sameweight(duck,girl). % by experiment

% ?- witch(girl).
